Logic Colloquium ’90
Proceedings of the Annual European Summer
Meeting of the Association for Symbolic Logic,
held in Helsinki, Finland
July 15 – 22, 1990

This volume, the second publication in the Lecture Notes in Logic series, is the proceedings of the Association for Symbolic Logic meeting held in Helsinki, Finland, in July 1990. It contains eighteen papers by leading researchers, covering all fields of mathematical logic from the philosophy of mathematics, through model theory, proof theory, recursion theory, and set theory, to the connections of logic to computer science. The articles published here are still widely cited and continue to provide ideas for ongoing research projects.

Table of Contents

A note on the ordinal analysis of KPM.
Wilfried Buchholz

On the geometry of U-rank 2 types.
Steven Buechler and Ludomir Newelski

Definability and global degree theory.
S. Barry Cooper

About the irreflexivity hypothesis for free left distributive magmas.
Patrick Dehornoy